The leaders of the Senate Judiciary Committee are calling on President Donald Trump’s adviser and son-in-law Jared Kushner to turn over communications about WikiLeaks and a “Russian backdoor overture and dinner invite” they say he failed to previously disclose to investigators.

Committee chair Sen. Chuck Grassley (R-Iowa) and ranking member Sen. Dianne Feinstein (D-Calif.) sent a letter to Kushner’s attorney Thursday requesting he provide additional information to aid the committee’s investigation into whether Trump’s campaign officials actively colluded with the Russian government to influence the outcome of the 2016 election. According to the letter, the committee became aware of several communications Kushner failed to disclose because other witnesses gave them the documents.

Among those documents is a September 2016 email regarding WikiLeaks that Kushner forwarded to another campaign official. The Atlantic reported earlier this week that Donald Trump Jr., the president’s eldest son, had communicated with WikiLeaks via Twitter during the campaign and shared the first message he received from the organization with Kushner and other campaign officials. Kushner then forwarded Trump Jr.’s message to Hope Hicks, then Trump’s campaign press secretary.

A second correspondence of interest is a “Russian backdoor overture and dinner invite” that Kushner also forwarded. The committee also requested Kushner’s attorney hand over emails from Sergei Millian, a Russian-American businessman, that Kushner was copied on.

The committee wants Kushner’s legal team to provide the documents, as well as communications Kushner had with former National Security Adviser Michael Flynn and further information on Kushner’s security clearance, to them by Nov. 27.

Kushner has denied colluding with Russian officials, and has claimed he has been “fully transparent” with investigators probing his father-in-law’s campaign.

“Let me be very clear: I did not collude with Russia, nor do I know of anyone else in the campaign who did so,” he said in a statement in July.

Kushner previously failed to disclose contacts with Russians, including his business ties to a Russian oligarch who helped Russian government institutions invest in Facebook and Twitter. He also omitted foreign contacts from his security clearance forms, as well as meetings with the Russian ambassador to the U.S. and the head of a Russian state-owned bank.